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Makita S.,Sasebo College of Technology | Nagata K.,Japan National Institute of Advanced Industrial Science and Technology
Advanced Robotics | Year: 2016

In partial caging, an object is partially constrained by robots and is able to escape from there. Although complete caging ensures the hand never releases the confined object, insufficient degrees of freedom of robots does not often satisfy the conditions for caging. Partial caging, however, can be accomplished even by robots having such mechanical restriction. We consider a case that an object moves in the semi-closed region formed by a planar robot hand with two fingers, as an example of partial caging in two-dimensional space. Then the parameters of fingers: joint angles interfere in the object motion to escape from the hand through the gap between the fingertips. Some simulation results show differences of difficulty of escaping according to arrangement of fingers, and factors interfering in the difficulty are analyzed. Additionally, we also evaluate ease of entering the hand through the gap and define an ability index of robot hand for partial caging with the above two evaluation scores. Then a high index score indicates that the hand assumed to be able to capture objects easily and confine it without any finger motion. It can be utilized for mechanical design and controlling strategies of robots in capturing objects. © 2016 Taylor & Francis and The Robotics Society of Japan Source

Makita S.,Sasebo College of Technology | Nagata K.,Japan National Institute of Advanced Industrial Science and Technology
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2015

In caging, an object is geometrically confined by position-controlled robots and never escapes from the constraint. Caging has some advantages over conventional grasping, and its applications have been performed not only in 2D but also in 3D scenes with various actual robots. However, the conditions of complete caging are not always satisfied due to limited robot configuration. This paper studies partial caging, in which an object is incompletely confined by robots or obstacles and is able to escape from the constraint. As an example of partial caging, a circular object moving in the planar hand is considered. We investigate an effect of arrangement of its fingertips, which prevents the object from escaping outside through the gap between the fingertips. Some simulation results show differences of difficulty of escaping for the object according to width of the gap and angle of the fingers. In addition, ease of entering the hand through the gap of the fingers is also evaluated. From these two scores on partial caging, we define an ability index for the hand, which represents the hand can easily capture an object and confine it without any finger motion. © 2015 IEEE. Source

Furusato T.,Kumamoto University | Ihara T.,Sasebo College of Technology | Kiyan T.,Kinki University | Katsuki S.,Kumamoto University | And 2 more authors.
IEEE Transactions on Plasma Science | Year: 2012

This paper deals with the initiation mechanism of a negative nanosecond pulsed discharge in supercritical (SC) carbon dioxide that was examined in detail using Schlieren and photomultiplier techniques. A negative pulsed voltage with a rise time of about 90 ns and half-width of 410 ns was applied to the point electrode. The experimental results show that: 1) The negative primary streamer was of a form quite different than that of a positive one: a bushlike negative streamer and a filamentlike positive streamer; 2) a drastic change in the density dependence of streamer initiation voltage appeared around the subcritical phase in the characteristics for streamer initiation voltage versus medium density; and 3) a shock wave of speed 1-1.5 Mach began growth following a delay of around 50 ns from the streamer initiation. It was predicted from the analysis of the experimental results that the drastic change in the streamer initiation voltage versus medium density characteristics may be due to a transition between the two types of generation mechanisms of the initial electron: electron detachment from negative ions in the gas phase and field electron emission from the point electrode in the SC and liquid phases. The shock wave was presumed to be caused by thermal relaxation of the vibrational energy in carbon dioxide molecules in a decay process of the primary streamer. © 1973-2012 IEEE. Source

Takeichi T.,Toyohashi University of Technology | Kano T.,Toyohashi University of Technology | Agag T.,Toyohashi University of Technology | Kawauchi T.,Toyohashi University of Technology | Furukawa N.,Sasebo College of Technology
Journal of Polymer Science, Part A: Polymer Chemistry | Year: 2010

High-molecular-weight polybenzoxazine prepolymers containing polydimethylsiloane unit in the main-chain have been synthesized from α,ω-bis(aminopropyl)polydimethylsiloxane (PDMS) (molecular weight = 248, 850, and 1622) and bisphenol-A with formaldehyde. Moreover, another type of prepolymers was prepared using methylenedianiline (MDA) as codiamine with PDMS. The weight average molecular weight of the obtained prepolymers was estimated from size exclusion chromatography to be in the range of 8000-11,000. The chemical structures of the prepolymers were investigated by 1H NMR and IR analyses. The prepolymers gave transparent free standing films by casting their dioxane solution. The prepolymer films after thermally cured up to 240 °C gave brown colored transparent and flexible polybenzoxazine films. Tensile test of the films revealed that the elongation at break increased with increasing the molecular weight of PDMS unit. Dynamic mechanical analysis of the thermosets showed that the T gs were as high as 238-270 °C. The thermosets also revealed high thermal stability as evidenced by the 5% weight loss temperatures in the range of 324-384 °C from thermogravimetic analysis. © 2010 Wiley Periodicals, Inc. Source

Kaneda Y.,Tokyo Institute of Technology | Sadahiro T.,Sasebo College of Technology | Yamakita M.,Tokyo Institute of Technology
Proceedings of the SICE Annual Conference | Year: 2011

Differentiator is widely used to calculate derivative of measured signal in many fields. To improve characteristics of frequency responses, a differentiator using Richardson extrapolation and fractional delay has been proposed. However, to implement fractional delay, some sort of high-order interpolator is needed, which causes many problems. In this paper, to resolve the problems caused by the high-order interpolator, a higher sampling rate system is implemented on FPGA, which acts like a system using fractional delay. A way to implement the proposed method on FPGA is described, and its effectiveness is verified by some experiments. © 2011 SICE. Source

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